A conventional control disk for a belt retractor comprises an inertial disk and an actuating projection. A control disk of this type is part of a latching mechanism with which the belt reel of the belt retractor, on which the belt webbing is coiled, can be blocked by vehicle-sensitive or belt webbing-sensitive means against rotation in the uncoiling direction. The latching mechanism of such a belt retractor is known, this being the reason why it is only briefly mentioned in the following.
The control disk of the latching mechanism can be rotated relatively to the belt reel to a limited extent. When the latching mechanism is activated in a vehicle-sensitive manner, i.e. by exceeding a predetermined acceleration or deceleration of the vehicle, or in a belt webbing sensitive manner, i.e. by exceeding a predetermined rotational acceleration of the belt reel due to tensile forces acting in the belt webbing, a rotation of the disk relatively to the belt reel occurs, as a result of which the actuating projection is swiveled into an activating position so that the belt reel is coupled non-rotatably to a control lever or a similar functional part which on rotation of the belt reel in the uncoiling direction activates a load-bearing blocking pawl and thus causes blocking of the belt reel. The belt reel is then blocked in the uncoiling direction.
More recently, belt-tensioning means are finding increasing use by which, after actuation, the so-called belt slack of the seat belt system is eliminated so that the vehicle occupant is involved as early as possible in a deceleration of the vehicle. In particular, buckle tensioners are known, which displace the belt buckle such that the seat belt is tensioned, and retractor tensioners which rotate the belt reel in the coiling direction so that excess belt webbing is taken up. In both systems, high acceleration of the belt reel and the functional parts connected thereto materializes, i.e. in the case of a buckle tensioner in the uncoiling direction of the belt webbing and in the case of a retractor tensioner in the coiling direction of the belt webbing. These high accelerations might result in damage to the functional parts of the latching mechanism so that following a tensioning action proper functioning of the belt retractor would no longer be assured. This is why it may be provided for that certain parts of the belt retractor are decoupled from the belt reel as soon as an excessively high rotational acceleration of the belt reel occurs; it being known, for example, to provide the control disk with a front face toothing which cooperates with an assigned gear toothing on the belt reel, the control disk being elastically loaded in the direction of the belt reel. In this way a slipping clutch is achieved by means of which the control disk can be decoupled from the belt reel as soon as a predetermined rotational acceleration of the latter occurs.